People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

Autism Spectrum Test Only Necessary For Kids With Early Signs Of Autism; Experts Nix Universal Screening

Intensive therapy following early detection of an autism spectrum disorder is believed to lessen the severity of a child's symptoms and in some cases can help mainstream a child. Yet, most children with autism are not diagnosed until age 4 or even older, according to the Centers for Disease Control and Prevention. If urgency is an issue, should we routinely screen all toddlers for this disorder? In a new statement, the United States Preventive Services Task Force (USPSTF) says more evidence is needed to recommend universal early screening for autism.

This is not a recommendation against screening, the task force added, possibly clouding the picture for many a worried parent. The USPSTF is a volunteer panel of national experts in preventive and evidence-based medicine. Until more extensive research becomes available, these experts suggest families concerned about an individual child should discuss the situation with their health care providers, who should use their own professional judgement to decide whether and when to screen.

“While we are learning more about autism every day, there is still much we don’t know about screening for autism,” said Dr. David Grossman, vice chair of the task force, in a brief video accompanying the new statement.

One in Every 68 Children

Autism spectrum disorder is considered a developmental disorder, meaning children with this disorder do not achieve some of the milestones of typical development or lose abilities they once had. Children with autism find it difficult to communicate with other people and are repetitive in their behavior. That said, symptoms often vary from child to child.

In fact, the term “spectrum” refers to autism's wide range of possible symptoms, levels of disability, and positive skills. Some children may not make eye contact, others may appear incapable of understanding simple instructions. Some become obsessed with a particular object, others demonstrate noteworthy abilities. As they age, some people with autism learn to function more or less normally, while others require substantial support to perform even basic activities.

Some doctors believe early detection is important because early treatment can help cultivate new connections around faulty neural pathways in a young child’s brain. Following a careful evaluation of evidence, though, the task force shrinks from recommending universal screening for autism in young children.

Not Enough Research

“Inadequate direct evidence” exists for the benefits of screening toddlers and preschool-age children when no concerns of autism have been raised by family members, caregivers, or health care professionals, the task force decided. No existing studies “focus on the clinical outcomes of children identified with ASD through screening.” At the same time, the task force believes the harms of screening and subsequent interventions are likely to be small.

Ultimately, “evidence is lacking, of poor quality, or conflicting,” the members say, leading them to conclude “the balance of benefits and harms [of screening] cannot be determined.”

“The task force supports improved awareness of the symptoms of autism and efforts by families, clinicians, and researchers to help children with autism live a better life," said Grossman.